1. Field of the Invention
This invention relates to a method for forming a pattern, to an imprint mold to be manufactured by this pattern forming method, and to a method of manufacturing a magnetic recording medium wherein this imprint mold is employed.
2. Description of the Related Art
Since the invention of the magnetic recording medium, the recording density thereof has continued to increase year by year and, even today, this trend continues.
Although patterned media may be effective means for realizing a recording density of as high as the tera-bit class, the size of the cell required for achieving such a high recording density is limited to as small as 30-20 nm or less. Such a fine microfabrication of a cell can be made possible by drawing a fine pattern by an electron beam, though this takes a long time. Therefore, the media worked in this manner would become very high in price.
It has been proposed to overcome this problem by employing a method wherein the patterned media are manufactured by taking advantage of the phase separation of a diblock copolymer, as described in IEEE Trans. Magn. Vol. 38, pp. 1949, K. Naito et al.; and in JP-A 2004-342226 (KOKAI). More specifically, according to this method, the diblock copolymer, consisting of polystyrene and polymethylene methacrylate, for example is subjected to phase separation to form a dot pattern, which is subsequently transferred onto a magnetic film to create magnetic dots to be used as recording cells. Owing to this phase separation of the diblock copolymer, it is possible to form a circular dot pattern which is arranged in the closest type of packing.
In the case of the magnetic recording apparatus having patterned media mounted thereon, there is the possibility that two or more recording cells may be erroneously wrought or read out en bloc by the recording head thereof. If it is possible to optimize the conditions such as the array of magnetic dots and the width of track in conformity with the recording head, it may be possible to obviate such a possibility. It is proposed in JP-A 2004-265474 (KOKAI) to form a dot pattern through the phase separation of a diblock copolymer in such a manner as to create the configuration of a bit in conformity with the locus of the configuration of the recording head. However, even with the method of forming a dot pattern through the phase separation of a diblock copolymer, it has been difficult to optimize the conditions such as the array of magnetic dots and the width of track in conformity with the configuration of the recording head.